Handheld electronic devices, such as mobile phones, personal digital assistants (PDAs), pocket personal computers (PCs), gamepads, and camcorders, generally have multiple of buttons that allow one to interface with the device by inputting information. The capabilities of these devices are increasing while their size and weight are decreasing to enhance their portability. For example, mobile phones, in addition to their traditional role as voice-communication devices, now include functions traditionally associated with other devices, such as electronic games, PDAs, and digital cameras. At the same time, consumers seek smaller, lighter devices.
To support these multiple functions, a screen display is often used. Thus, the area on devices devoted to user input, i.e., the activating or input area, is becoming increasingly complex in terms of the number of functions available to be input, while the physical size of the input area is decreasing. Moreover, the available size of the input area must compete with the size of the visual display.
To permit effective interaction with these devices, visual and audio cues or feedback are provided by the conventional device. In addition to conventional visual and audio feedback, some of these devices attempt to enhance the effectiveness of device feedback by providing tactile cues or feedback. Some devices utilize structural tactile methods. One such example is to provide raised surfaces on the input surface, e.g., keypad, of the device. Such methods, however, are inherently static and thus cannot offer a wide array of, or effective, tactile feedback.
Active methods of providing tactile feedback include incorporating haptics into handheld electronic devices. These active methods of providing haptic cues generally include vibrating the entire device. Some devices have incorporated haptic feedback into a surface of the device instead of vibrating the entire device. In such devices, the haptic feedback is provided to the input area, i.e., the activating area. However, the limited size of the input area in a handheld device provides a very limited area in which to provide meaningful haptic feedback. Furthermore, the amount of physical contact with the input area is generally limited to a small surface of a finger while inputting information to the device. Moreover, in typical active methods, the frequencies at which the devices are vibrated have been in very limited ranges—typically between 20 Hz and 28 Hz. The number of haptic cues that can be conveyed in such a range is very limited.